What is the exact thickness of plates of iron in the 1870s?

[Moony]

Hello "crew"!

 

Dealing with early colliers/coasters I collidated with the question of the thickness of iron (NOT steel) plates - revited on the formers to form the hull. 

As I'm building in 1/36 I'm forced to give them the very exact and right dimensions... this is the source of my outlandish question.

The surviving coasters (S/S Robin, S/S VIC 32, S/S John Oxley or S/S Sir Walter Scott) are all steel hulled - so these information is not very helpfull to me.

 

About the sailing ship iron hull building is said for the 1860s: "The earliest iron hull plates were very small by today's standards, no more than 6 ft by 2 ft 6 in. by approximately 3/4 to 7/8 in. thick, and with about 18 in. frame spacing."

 

Do you know anything about the newcastle iron plates measurements used for steamers in the first half of the 70th?

 

Here a drawing from mcjazz.f2s.com :

Edited January 22, 2016 by Moony

[grsjax]

Just my opinion so take it for what it is worth.  I would say that each builder decided what size and thickness of plate to use based on experiance and availability.  I don't think there was any standard in the industry.  I know Lloyds published a set of specifications for insurance purposes but I do not know exactly when that was.  If you know what Lloyds classification the ship was you could check to see what Lloyds requirements were but that would be a guide not an exact size.

[Jim Lad]

If it's any help, Lloyds rules for 1890 give the outer plate thickness for iron ships of the size of the Warkworth as varying between 3/8" and 5/16".  Can't go earlier for you, but I wouldn't think that there'd be much of a change over the two decades.

 

John

[Doreltomin]

Hi Moony,

 

The image you posted actually comes from a book written by George Frederick Campbell which is called "China tea clippers" , 1954. 

 

As for your question, back in 1860 there were two situations: there were either well known shipbuilding companies which gradually switched from wooden construction to iron, therefore they had to buy iron profiles including iron plates from a local supplier or there was the inverse situation where an iron company extended their trade into shipbuilding. There are also known cases when two well known firms, one in iron working, the other in shipbuilding, start to work together. In both cases they borrowed some practices from the previous wooden construction like the distance between frames. In a lengthy process of trial and error they learned the proper thickness of an iron plate for a said distance between the frames, just as in the case of the wooden builds. Then they bought the appropriate plates either from a local supplier or had them made to specifications. So the thickness varied with the distance between frames, which in turn varied with the length of the ship, and their choice was more or less the job of the ship designer. Smaller ships had a smaller distance between the frames, bigger ships had more. 

 

Just to make you an image, the plates were offered in a wide range of thicknesses, the standard being much the same as today: https://www.tedpella.com/company_html/gauge.htm

 

So I am afraid the only correct answer to your question is: find the original drawings of the ship and you will find also the correct thickness of the plates, there is no standard!